linux驱动(六):input(key)
本文主要探讨210的input子系统。
input子系统
input子系统包含:设备驱动层,输入核心层,事件驱动层
事件处理层：接收核心层上报事件选择对应struct input_handler处理,每个input_handler对象处理一类事件,同类事件的设备驱动共用同一handler
核心层：连接设备驱动层和事件处理层,为设备驱动层提供输入设备驱动接口(struct input_dev)以及输入设备驱动注册函数(input_register_device),为事件处理层提供输入事件驱动接口,通知事件处理层对事件处理
设备驱动层:获取硬件设备信息,并转换为核心层定义的规范事件后提交给核心层,每个设备均被描述为struct input_dev对象
结构体
input_dev结构体是硬件驱动层代表input设备结构体
// include/linux/input.h
struct input_dev {
const char *name; /* 设备名称 */
const char *phys; /* 设备在系统中的路径 */
const char *uniq; /* 设备唯一id */
struct input_id id; /* input设备id号 */
unsigned long propbit[BITS_TO_LONGS(INPUT_PROP_CNT)];
unsigned long evbit[BITS_TO_LONGS(EV_CNT)]; /* 设备支持的事件类型，主要有EV_SYNC，EV_KEY，EV_KEY,EV_REL,EV_ABS等*/
unsigned long keybit[BITS_TO_LONGS(KEY_CNT)]; /* 按键所对应的位图 */
unsigned long relbit[BITS_TO_LONGS(REL_CNT)]; /* 相对坐标对应位图 */
unsigned long absbit[BITS_TO_LONGS(ABS_CNT)]; /* 决定左边对应位图 */
unsigned long mscbit[BITS_TO_LONGS(MSC_CNT)]; /* 支持其他事件 */
unsigned long ledbit[BITS_TO_LONGS(LED_CNT)]; /* 支持led事件 */
unsigned long sndbit[BITS_TO_LONGS(SND_CNT)]; /* 支持声音事件 */
unsigned long ffbit[BITS_TO_LONGS(FF_CNT)]; /* 支持受力事件 */
unsigned long swbit[BITS_TO_LONGS(SW_CNT)]; /* 支持开关事件 */
unsigned int hint_events_per_packet; /* 平均事件数*/
unsigned int keycodemax; /* 支持最大按键数 */
unsigned int keycodesize; /* 每个键值字节数 */
void *keycode; /* 存储按键值的数组的首地址 */
int (*setkeycode)(struct input_dev *dev,
const struct input_keymap_entry *ke,
unsigned int *old_keycode);
int (*getkeycode)(struct input_dev *dev,
struct input_keymap_entry *ke);
struct ff_device *ff; /* 设备关联的反馈结构，如果设备支持 */
unsigned int repeat_key; /* 最近一次按键值，用于连击 */
struct timer_list timer; /* 自动连击计时器 */
int rep[REP_CNT]; /* 自动连击参数 */
struct input_mt *mt; /* 多点触控区域 */
struct input_absinfo *absinfo; /* 存放绝对值坐标的相关参数数组 */
unsigned long key[BITS_TO_LONGS(KEY_CNT)]; /* 反应设备当前的按键状态 */
unsigned long led[BITS_TO_LONGS(LED_CNT)]; /* 反应设备当前的led状态 */
unsigned long snd[BITS_TO_LONGS(SND_CNT)]; /* 反应设备当前的声音状态 */
unsigned long sw[BITS_TO_LONGS(SW_CNT)]; /* 反应设备当前的开关状态 */
int (*open)(struct input_dev *dev); /* 第一次打开设备时调用，初始化设备用 */
void (*close)(struct input_dev *dev); /* 最后一个应用程序释放设备事件，关闭设备 */
int (*flush)(struct input_dev *dev, struct file *file); /* 用于处理传递设备的事件 */
int (*event)(struct input_dev *dev, unsigned int type, unsigned int code, int value); /* 事件处理函数，主要是接收用户下发的命令，如点亮led */
struct input_handle __rcu *grab; /* 当前占有设备的input_handle */
spinlock_t event_lock; /* 事件锁 */
struct mutex mutex; /* 互斥体 */
unsigned int users; /* 打开该设备的用户数量（input_handle） */
bool going_away; /* 标记正在销毁的设备 */
struct device dev; /* 设备 */
struct list_head h_list; /* 设备所支持的input handle */
struct list_head node; /* 用于将此input_dev连接到input_dev_list */
unsigned int num_vals; /* 当前帧中排队的值数 */
unsigned int max_vals; /* 队列最大的帧数*/
struct input_value *vals; /* 当前帧中排队的数组*/
bool devres_managed; /* 表示设备被devres 框架管理，不需要明确取消和释放*/
};input_handler结构体是事件层代表事件处理器
// include/linux/input.h
struct input_handler {
void *private; /* 存放handle数据 */
void (*event)(struct input_handle *handle, unsigned int type, unsigned int code, int value);
void (*events)(struct input_handle *handle,
const struct input_value *vals, unsigned int count);
bool (*filter)(struct input_handle *handle, unsigned int type, unsigned int code, int value);
bool (*match)(struct input_handler *handler, struct input_dev *dev);
int (*connect)(struct input_handler *handler, struct input_dev *dev, const struct input_device_id *id);
void (*disconnect)(struct input_handle *handle);
void (*start)(struct input_handle *handle);
const struct file_operations *fops;
bool legacy_minors;
int minor;
const char *name; /* 名字 */
const struct input_device_id *id_table; /* input_dev匹配用的id */
struct list_head h_list; /* 用于链接和handler相关的handle，input_dev与input_handler配对之后就会生成一个input_handle结构 */
struct list_head node; /* 用于将该handler链入input_handler_list，链接所有注册到内核的所有注册到内核的事件处理器 */
};
input_handle结构体属于核心层代表配对input设备(input_dev)与input事件处理器(input_handler)
// include/linux/input.h
struct input_handle {
void *private; /* 数据指针 */
int open; /* 打开标志，每个input_handle 打开后才能操作 */
const char *name; /* 设备名称 */
struct input_dev *dev; /* 指向所属的input_dev */
struct input_handler *handler; /* 指向所属的input_handler */
struct list_head d_node; /* 用于链入所指向的input_dev的handle链表 */
struct list_head h_node; /* 用于链入所指向的input_handler的handle链表 */
};Evdev字符设备事件结构体
/* drivers/input/evdev.c */
struct evdev {
int open; /* 设备被打开的计数 */
struct input_handle handle; /* 关联的input_handle */
wait_queue_head_t wait; /* 等待队列，当前进程读取设备，没有事件产生时，
进程就会sleep */
struct evdev_client __rcu *grab; /* event响应 */
struct list_head client_list; /* evdev_client链表，说明evdev设备可以处理多个 evdev _client，可以有多个进程访问evdev设备 */
spinlock_t client_lock;
struct mutex mutex;
struct device dev;
struct cdev cdev;
bool exist; /* 设备存在判断 */
};evdev_client字符设备事件响应结构体
struct evdev_client {
unsigned int head; /* 动态索引，每加入一个event到buffer中，head++ */
unsigned int tail; /* 动态索引，每取出一个buffer中到event，tail++ */
unsigned int packet_head; /* 数据包头部 */
spinlock_t buffer_lock;
struct fasync_struct *fasync; /* 异步通知函数 */
struct evdev *evdev;
struct list_head node; /* evdev_client链表项 */
int clkid;
bool revoked;
unsigned int bufsize;
struct input_event buffer[]; /* 用来存放input_dev事件缓冲区 */
};
evdev_handler事件处理函数结构体
/* drivers/input/input.c */
static struct input_handler evdev_handler = {
.event = evdev_event, /* 事件处理函数， */
.events = evdev_events, /* 事件处理函数， */
.connect = evdev_connect, /* 连接函数，将事件处理和输入设备联系起来 */
.disconnect = evdev_disconnect, /* 断开该链接 */
.legacy_minors = true,
.minor = EVDEV_MINOR_BASE,
.name = "evdev", /* handler名称 */
.id_table = evdev_ids, /* 断开该链接 */
};input_event结构体(按键编码信息)
/* drivers/input/evdev.c */
struct input_event {
struct timeval time; /* 事件发生的时间 */
__u16 type; /* 事件类型 */
__u16 code; /* 事件码 */
__s32 value; /* 事件值 */
};
inputcore
subsys_initcall(input_init);
module_exit(input_exit);static int __init input_init(void)
{
int err;
input_init_abs_bypass();
err = class_register(&input_class);
if (err) {
printk(KERN_ERR "input: unable to register input_dev class\n");
return err;
}
err = input_proc_init();
if (err)
goto fail1;
err = register_chrdev(INPUT_MAJOR, "input", &input_fops);
if (err) {
printk(KERN_ERR "input: unable to register char major %d", INPUT_MAJOR);
goto fail2;
}
return 0;
fail2: input_proc_exit();
fail1: class_unregister(&input_class);
return err;
}struct class input_class = {
.name = "input",
.devnode = input_devnode,
};#define INPUT_MAJOR 13static const struct file_operations input_fops = {
.owner = THIS_MODULE,
.open = input_open_file,
}; class_register注册输入设备类/sys/class/input
input_proc_init注册proce文件/proc/bus/input
register_chrdevs注册设备注册,主设备号为13
static int input_open_file(struct inode *inode, struct file *file)
{
struct input_handler *handler;
const struct file_operations *old_fops, *new_fops = NULL;
int err;
err = mutex_lock_interruptible(&input_mutex);
if (err)
return err;
/* No load-on-demand here? */
handler = input_table[iminor(inode) >> 5];
if (handler)
new_fops = fops_get(handler->fops);
mutex_unlock(&input_mutex);
/*
* That's _really_ odd. Usually NULL ->open means "nothing special",
* not "no device". Oh, well...
*/
if (!new_fops || !new_fops->open) {
fops_put(new_fops);
err = -ENODEV;
goto out;
}
old_fops = file->f_op;
file->f_op = new_fops;
err = new_fops->open(inode, file);
if (err) {
fops_put(file->f_op);
file->f_op = fops_get(old_fops);
}
fops_put(old_fops);
out:
return err;
}static const struct file_operations input_fops = {
.owner = THIS_MODULE,
.open = input_open_file,
};static struct input_handler *input_table[8];
handler = input_table[iminor(inode) >> 5]; 获取子设备号并除以32的值为input驱动数组号,来获取对应input_handler中的fops
input_table为input_register_handler函数注册时填充
事件处理层
int input_register_handler(struct input_handler *handler)
{
struct input_dev *dev;
int retval;
retval = mutex_lock_interruptible(&input_mutex);
if (retval)
return retval;
INIT_LIST_HEAD(&handler->h_list);
if (handler->fops != NULL) {
if (input_table[handler->minor >> 5]) {
retval = -EBUSY;
goto out;
}
input_table[handler->minor >> 5] = handler;
}
list_add_tail(&handler->node, &input_handler_list);
list_for_each_entry(dev, &input_dev_list, node)
input_attach_handler(dev, handler);
input_wakeup_procfs_readers();
out:
mutex_unlock(&input_mutex);
return retval;
}
static int __init evdev_init(void)
{
return input_register_handler(&evdev_handler);
}依据evdev.c分析input_register_hndler
static struct input_handler evdev_handler = {
.event = evdev_event,
.connect = evdev_connect,
.disconnect = evdev_disconnect,
.fops = &evdev_fops,
.minor = EVDEV_MINOR_BASE,
.name = "evdev",
.id_table = evdev_ids,
};static const struct file_operations evdev_fops = {
.owner = THIS_MODULE,
.read = evdev_read,
.write = evdev_write,
.poll = evdev_poll,
.open = evdev_open,
.release = evdev_release,
.unlocked_ioctl = evdev_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = evdev_ioctl_compat,
#endif
.fasync = evdev_fasync,
.flush = evdev_flush
}#define EVDEV_MINOR_BASE 64static const struct input_device_id evdev_ids[] = {
{ .driver_info = 1 }, /* Matches all devices */
{ }, /* Terminating zero entry */
};static void evdev_event(struct input_handle *handle,
unsigned int type, unsigned int code, int value)
{
struct evdev *evdev = handle->private;
struct evdev_client *client;
struct input_event event;
struct timespec ts;
ktime_get_ts(&ts);
event.time.tv_sec = ts.tv_sec;
event.time.tv_usec = ts.tv_nsec / NSEC_PER_USEC;
event.type = type;
event.code = code;
event.value = value;
rcu_read_lock();
client = rcu_dereference(evdev->grab);
if (client)
evdev_pass_event(client, &event);
else
list_for_each_entry_rcu(client, &evdev->client_list, node)
evdev_pass_event(client, &event);
rcu_read_unlock();
wake_up_interruptible(&evdev->wait);
}static int evdev_connect(struct input_handler *handler, struct input_dev *dev,
const struct input_device_id *id)
{
struct evdev *evdev;
int minor;
int error;
for (minor = 0; minor < EVDEV_MINORS; minor++)
if (!evdev_table[minor])
break;
if (minor == EVDEV_MINORS) {
printk(KERN_ERR "evdev: no more free evdev devices\n");
return -ENFILE;
}
evdev = kzalloc(sizeof(struct evdev), GFP_KERNEL);
if (!evdev)
return -ENOMEM;
INIT_LIST_HEAD(&evdev->client_list);
spin_lock_init(&evdev->client_lock);
mutex_init(&evdev->mutex);
init_waitqueue_head(&evdev->wait);
dev_set_name(&evdev->dev, "event%d", minor);
evdev->exist = 1;
evdev->minor = minor;
evdev->handle.dev = input_get_device(dev);
evdev->handle.name = dev_name(&evdev->dev);
evdev->handle.handler = handler;
evdev->handle.private = evdev;
evdev->dev.devt = MKDEV(INPUT_MAJOR, EVDEV_MINOR_BASE + minor);
evdev->dev.class = &input_class;
evdev->dev.parent = &dev->dev;
evdev->dev.release = evdev_free;
device_initialize(&evdev->dev);
error = input_register_handle(&evdev->handle);
if (error)
goto err_free_evdev;
error = evdev_install_chrdev(evdev);
if (error)
goto err_unregister_handle;
error = device_add(&evdev->dev);
if (error)
goto err_cleanup_evdev;
return 0;
err_cleanup_evdev:
evdev_cleanup(evdev);
err_unregister_handle:
input_unregister_handle(&evdev->handle);
err_free_evdev:
put_device(&evdev->dev);
return error;
}int input_register_handle(struct input_handle *handle)
{
struct input_handler *handler = handle->handler;
struct input_dev *dev = handle->dev;
int error;
/*
* We take dev->mutex here to prevent race with
* input_release_device().
*/
error = mutex_lock_interruptible(&dev->mutex);
if (error)
return error;
/*
* Filters go to the head of the list, normal handlers
* to the tail.
*/
if (handler->filter)
list_add_rcu(&handle->d_node, &dev->h_list);
else
list_add_tail_rcu(&handle->d_node, &dev->h_list);
mutex_unlock(&dev->mutex);
/*
* Since we are supposed to be called from ->connect()
* which is mutually exclusive with ->disconnect()
* we can't be racing with input_unregister_handle()
* and so separate lock is not needed here.
*/
list_add_tail_rcu(&handle->h_node, &handler->h_list);
if (handler->start)
handler->start(handle);
return 0;
} input_register_handler为事件注册函数,struct input_handler为事件处理结构体
evdev_init调用input_register_handler和struct input_handler evdev_handler注册evdev设备事件
evdev_fops为edev类型设备操作函数,EVDEV_MINOR_BASE为64存在input_table[2]中
id_table为handler支持的输入设备(input_dev->id==input_handler->id_table,调用connect)
设备驱动层
int input_register_device(struct input_dev *dev)
{
static atomic_t input_no = ATOMIC_INIT(0);
struct input_handler *handler;
const char *path;
int error;
/* Every input device generates EV_SYN/SYN_REPORT events. */
__set_bit(EV_SYN, dev->evbit);
/* KEY_RESERVED is not supposed to be transmitted to userspace. */
__clear_bit(KEY_RESERVED, dev->keybit);
/* Make sure that bitmasks not mentioned in dev->evbit are clean. */
input_cleanse_bitmasks(dev);
/*
* If delay and period are pre-set by the driver, then autorepeating
* is handled by the driver itself and we don't do it in input.c.
*/
init_timer(&dev->timer);
if (!dev->rep[REP_DELAY] && !dev->rep[REP_PERIOD]) {
dev->timer.data = (long) dev;
dev->timer.function = input_repeat_key;
dev->rep[REP_DELAY] = 250;
dev->rep[REP_PERIOD] = 33;
}
if (!dev->getkeycode)
dev->getkeycode = input_default_getkeycode;
if (!dev->setkeycode)
dev->setkeycode = input_default_setkeycode;
dev_set_name(&dev->dev, "input%ld",
(unsigned long) atomic_inc_return(&input_no) - 1);
error = device_add(&dev->dev);
if (error)
return error;
path = kobject_get_path(&dev->dev.kobj, GFP_KERNEL);
printk(KERN_INFO "input: %s as %s\n",
dev->name ? dev->name : "Unspecified device", path ? path : "N/A");
kfree(path);
error = mutex_lock_interruptible(&input_mutex);
if (error) {
device_del(&dev->dev);
return error;
}
list_add_tail(&dev->node, &input_dev_list);
list_for_each_entry(handler, &input_handler_list, node)
input_attach_handler(dev, handler);
input_wakeup_procfs_readers();
mutex_unlock(&input_mutex);
return 0;
}static int input_attach_handler(struct input_dev *dev, struct input_handler *handler)
{
const struct input_device_id *id;
int error;
id = input_match_device(handler, dev);
if (!id)
return -ENODEV;
error = handler->connect(handler, dev, id);
if (error && error != -ENODEV)
printk(KERN_ERR
"input: failed to attach handler %s to device %s, "
"error: %d\n",
handler->name, kobject_name(&dev->dev.kobj), error);
return error;
}list_add_tail(&dev->node, &input_dev_list);
list_for_each_entry(handler, &input_handler_list, node)input_attach_handler(dev, handler); 将要注册input_dev驱动设备放在input_dev_list链表中,调用input_attach_handler函数，将每个input_handle的id_table进连接接
注册input_handler类同设备注册通过inputhandle将input_handler和input_dev连接(id匹配)
int input_register_handler(struct input_handler *handler)
{
......
list_add_tail(&handler->node, &input_handler_list);
list_for_each_entry(dev, &input_dev_list, node)
input_attach_handler(dev, handler);
......
}核心层提供给设备驱动层的接口函数
struct input_dev *input_allocate_device(void);
分配input_dev内存
void input_set_capability(struct input_dev *dev, unsigned int type, unsigned int code);
设置输入设备上报事件，input_set_capability(dev, EV_KEY, KEY_E);
dev:input_dev结构体,type上报事件类型,code上报具体事件
int input_register_device(struct input_dev *dev);
input核心层注册设备demo:
210内核自带轮循方式检测按键，自写中断方式
button-x210.c
#include
#include
#include
#include
#include
#include
#include
#include
#define BUTTON_IRQ_LEFT IRQ_EINT2
static struct input_dev *button_dev;
static irqreturn_t button_interrupt(int irq, void *dummy)
{
int flag;
//中断产生,设置gpio为输入模式下获取gpio号
s3c_gpio_cfgpin(S5PV210_GPH0(2), S3C_GPIO_SFN(0x0));
flag = gpio_get_value(S5PV210_GPH0(2));
//重新置为中断模式
s3c_gpio_cfgpin(S5PV210_GPH0(2), S3C_GPIO_SFN(0x0f));
//上报按键中断事件
input_report_key(button_dev, KEY_LEFT, !flag);
//同步按键中断
input_sync(button_dev);
return IRQ_HANDLED;
}
static int __init button_init(void)
{
int error;
//申请gpio
error = gpio_request(S5PV210_GPH0(2), "GPH0_2");
if(error)
{
printk("button-x210.c: request gpio GPH0(2) fail");
return -EBUSY;
}
//配置gpio为中断模式
s3c_gpio_cfgpin(S5PV210_GPH0(2), S3C_GPIO_SFN(0x0f));
//申请中断
if (request_irq(BUTTON_IRQ_LEFT, button_interrupt, 0, "button", NULL))
{
printk(KERN_ERR "button-x210.c: Can't allocate irq %d\n", BUTTON_IRQ_LEFT);
goto err_free_gpio;
return -EBUSY;
}
//申请设备内存
button_dev = input_allocate_device();
if (!button_dev)
{
printk(KERN_ERR "button-x210.c: Not enough memory\n");
error = -ENOMEM;
goto err_free_irq;
}
//设备初始化
button_dev->name = "x210";
//设置设备上报事件
input_set_capability(button_dev, EV_KEY, KEY_LEFT);
//设备注册
error = input_register_device(button_dev);
if (error)
{
printk(KERN_ERR "button-x210.c: Failed to register device\n");
goto err_free_dev;
}
return 0;
err_free_dev:
input_free_device(button_dev);
err_free_irq:
free_irq(BUTTON_IRQ_LEFT, button_interrupt);
err_free_gpio:
gpio_free(S5PV210_GPH0(2));
return error;
}
static void __exit button_exit(void)
{
input_unregister_device(button_dev);
input_free_device(button_dev);
free_irq(BUTTON_IRQ_LEFT, NULL);
gpio_free(S5PV210_GPH0(2));
}
module_init(button_init);
module_exit(button_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("cxb");
MODULE_DESCRIPTION("button module");
MODULE_ALIAS("button"); button.c
#include
#include
#include
#include
#include
#include
#define X210_KEY "/dev/input/event2"
int main(void)
{
int fd = -1, ret = -1;
struct input_event ev;
fd = open(X210_KEY, O_RDONLY);
if (fd < 0)
{
perror("open");
return -1;
}
while (1)
{
memset(&ev, 0, sizeof(struct input_event));
ret = read(fd, &ev, sizeof(struct input_event));
if (ret != sizeof(struct input_event))
{
perror("read");
close(fd);
return -1;
}
printf("-------------------------\n");
printf("type: %hd\n", ev.type);
printf("code: %hd\n", ev.code);
printf("value: %d\n", ev.value);
printf("\n");
}
close(fd);
return 0;
} 操作流程：
cd /root/kernel/arch/arm/mach-s5pv210
rm button-x210.o
vim Makefile
#obj-$(CONFIG_MACH_SMDKV210) += button-x210.o
make -j8
